[tim333]

Cheap in comparison to the vessels they attacked.

In Ukraine the Russians had to move the fleet out of Sevastopol because of Ukrainian naval drone attacks, mostly to Novorossiysk and then recently have had to block that in with barges dropped across the entrance to try to prevent underwater drones getting in like the one that damaged a sub there last week.

The recent drone attack on the oil tanker Qendil in the Med was an interesting new one. 2000 km from Ukraine and they seem to have used drones to drop grenades or similar on the ship.